Obesity may be the most important medical problem in American Society. The factors that may lead to the onset and maintenance of the obese state are not clear. The work in this study will monitor the serum levels of a series of meal-related hormones and peptides in response to two standard meals in a group of 10 obese children between the ages of 12 and 17 both before and after weight loss. Their results will be compared to those of 10 lean children. The goal is to ascertain whether any factor may be important in the hyperphagia of the obese state. We anticipate that by elucidating the effect of meals on the levels of those serum hormones that control fat accumulation and satiety in lean young subjects, we will be able to dissect out the changes that are important in the genesis of hyperphagia and obesity.